I always compost them and apart from the seeds that have already dropped where they are going I havent had a problem with the compost. if you arent certain then you can always pull the seeds off and bin them in the municipal waste.

i still get plants germinating from where they grew but not from any of the composted one. perhaps my heap gets hot enough to kil them. it just seems a shame not to compost the wonderfully fleshy leaves.